Blood samples and brain scans

The researchers looked at blood samples from 273 participants who also had brain scans to assess the levels of amyloid protein in the brain.

Burnham and colleagues found seven proteins in the blood samples that, together with a person's age and cognitive test results, could be used to develop a mathematical formula to predict levels of amyloid in the brain with 80 per cent accuracy.

They validated their findings by showing the formula correctly predicted the level of amyloid protein in the brains of 82 people, from a separate brain scan study.

The researchers are also in the process of fully validating the formula on the other participants in the AIBL study.

At this stage Burnham and colleagues are not sure how the blood markers relate to Alzheimer's disease.

A patent has been filed by Burnham and two other colleagues covering the blood marker formula and two of the research team members are consultants with Prana Biotechnology.

'Verified by the data'

Neuroscientist Dr Bryce Vissel of the Garvan Institute of Medical Research welcomes the conclusions that blood markers could be used to predict people's risk of Alzheimer's.

"It looks to be verified by the data," says Vissel.

He supports the findings despite his argument that inflammation rather than amyloid protein is more likely to cause Alzheimer's disease.

"Regardless of whether the amyloid hypothesis is right or not we actually need to start treatment a lot earlier and we have to find better ways to diagnose the disease."

Vissel says while there is some debate about whether amyloid is the best early marker of Alzheimer's disease, he agrees amyloid plaque appears in the brain of the vast majority of people with the condition.

"No one debates amyloid load is a good indicator of Alzheimer's. Whether it's the cause of Alzheimer's is another issue."

Vissel says he is excited by the findings that blood markers found by Burnham include markers he associates with inflammation.